1. Field of the Invention
The present invention relates to a method and apparatus that uses an electron beam or other charged particle beams to inspect an object to be inspected.
2. Description of the Related Arts
Conventionally, in semiconductor manufacturing techniques, an optical inspection apparatus is used to inspect a mask, a wafer, or the like. The types of those inspections include a pattern defect inspection and a foreign material inspection, and the foreign material is, for example, a particle. An optical inspection apparatus irradiates laser or other light onto a sample, and detects light scattered by particles.
An optical inspection apparatus can inspect with a relatively high S/N and relatively high rate. However, the resolution is relatively low, and the detection sensitivity significantly decreases when the size of a defect is 50 nm or less, resulting in difficulty in detection.
For a pattern defect inspection, an inspection apparatus of a scanning electron microscope (SEM) type is used in order to inspect for fine pattern defects that cannot be inspected by an optical inspection apparatus. An SEM type inspection apparatus is configured to scan a sample with an electron beam as a charged particle beam, and can inspect even if the size of a pattern defect is 50 nm or less or, particularly, 20 nm or less. An SEM type inspection apparatus is disclosed, for example, in Japanese Patent Laid-Open Application No. 2007-40910.
As described above, an SEM type inspection apparatus is suitable for inspection for fine defects, and can detect a pattern defect of 50 nm or less. However, an SEM type inspection apparatus is not generally applied to a particle inspection. Applying an SEM type inspection apparatus to a particle inspection would require the pixel size of the SEM to be ½ to ⅓ of a particle or less in order to determine a particle, and would therefore take a significantly long time.
Moreover, no method for efficiently carrying out an inspection for a defect in a multilayer has yet been established in conventional inspection techniques. An inspection for a defect in a multilayer refers to an inspection for a foreign material buried in layers, or the like. An optical inspection apparatus and an SEM inspection apparatus can only detect defects on the surface of a sample and cannot detect defects in layers.
As above, conventional SEM-type inspection apparatuses can only be applied to a pattern defect inspection, but one inspection apparatus cannot carry out inspections for a plurality of types of defects. Specifically, one inspection apparatus would not be able to carry out a plurality of types of inspections including a pattern defect inspection, a foreign material inspection, and an inspection for a defect in a multilayer. This is because the plurality of types of inspections requires different detection methods and mechanisms, and therefore the inspection apparatuses could hardly be merged. Such a state is inconvenient to users, causes the inspection efficiency to decrease, and increases space required for the inspection apparatuses.